ul {
	list-style-type: none;
	/*去掉小点*/
	margin: 0px;
	padding: 0px;
}

a:link,a:visited { 
	/*去掉下划线*/
	text-decoration: none;
	display: block;
	background-color: gray;
	color: pink;
	width: 100px;
	text-align: center;
}

a:active,a:hover {
	background-color: green;
}